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Thread: Any Idea about Creatinine Clearance Test (GFR Estimation)

  1. #1
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    Default Any Idea about Creatinine Clearance Test (GFR Estimation)

    Hi All,

    I am regular visitor of the forum. But today I have reason to post something.

    I got an email from London branch saying they want a repeat Creatinine Clearance Test for my wife as her earlier report was out of normal range.

    My wife is 28 years old and She does not have any health issues. Can anyone in the forum suggest what is the normal range for the test (GFR).

    I am a Software Engineer working in London and my wife is an Manager in govt bank in India.

    Please suggest in any one has encountered such issues.

  2. #2
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    Hello and welcome. I hope someone will soon have an answer for you.

  3. #3
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    Hy Samay,

    this is what I found on-line:

    Glomerular Filtration Rate (GFR): Your GFR tells how much kidney function you have. It may be estimated from your blood level of creatinine. If your GFR falls below 30 you will need to see a kidney disease specialist (called a nephrologist), Your kidney doctor will speak to you about treatments for kidney failure like dialysis or kidney transplant. A GFR below 15 indicates that you need to start one of these treatments.

    more info http://www.kidney.org/professionals/KLS/GFR.cfm

    Hope it helps...but from what I know, 10% higher or lower indicators are still considered ok.

    Whishing you all the best!

  4. #4
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    We're going through creatinine hell with our youngest son right now. When our medicals were submitted May 2009, his creatinine was 1.00 mg/dL (upper range of normal for an adolescent boy, according to our GP), and the MA asked for a retest. Got the results yesterday -- 1.01 mg/dL.

    Per our GP, the upper range of normal for an adult is 1.30 mg/dL, so he thinks that further testing is unnecessary. The problem is that the MA may disagree, and we don't want to introduce further delays at this point. So, we're probably going to have him evaluated by a nephrologist or urologist (at our cost, mind -- insurance will not pay for specialists that the GP thinks are unnecessary) just to head off further questions.

    I think that part of the problem is that the lab results we receive do not estimate GFR for patients under 18 YO. I don't know why -- using the calculator that lida16 linked to above, I can easily calculate a GFR over 125 mL/min/1.73 for my son, which should be of no concern.

  5. #5
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    Hi lida16 and SKS,

    Thanks for your reply. From the discussion Can I conclude if GFR is above 30 that means Kindney is functioning properly.

  6. #6
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    Glomerular filtration rate (GFR) is the best overall index of kidney function.

    Normal GFR varies according to age, sex, and body size, and declines with age.

    I couldn't find any measure limits, sorry.

  7. #7
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    Quote Originally Posted by samay View Post
    Hi lida16 and SKS,

    Thanks for your reply. From the discussion Can I conclude if GFR is above 30 that means Kindney is functioning properly.
    The test your wife had (initially) was most likely a serum creatinine test--this is blood test that tells you how much creatinine was in the blood at the exact time the blood was drawn. From this number, the lab likely calculated a creatinine clearance, which is an estimate of GFR. [Here's a nice calculator, but make sure you are using the correct units everywhere: http://www.globalrph.com/crcl.htm]

    These calculations are truly estimates, and some would argue, not very good estimates. They work fairly well for "average" people--make that average men. As you deviate from the norm: on age, weight, gender, or serum creatinine levels, accuracy goes way down. Because of the way the calculation is set up, anybody who is young and/or tall can get away with a high serum creatinine, and still show up as normal when you use the calculation.

    A few things that will "artificially" raise serum creatinine:
    1) Dehydration
    2) Vigorous exercise
    3) Hgh muscle mass (body builders run high serum creatinine levels
    4) Drugs that affect creatinine elimination (I'm doing this from memory, but cimetidine is coming to mind; there are numerous other drugs that can damage the kidney--these will also raise serum creatinine.)

    Anyway, to answer your question: It is not safe to assume kidneys are functioning properly just because the calculation give you a result above 30. [That's more of a hypothetical answer: I am guessing your wife's serum creatinine was just a little high, and her clearance calculates to a number much higher than 30, or else her doctor would have done something about it when he/she received the results.]

  8. #8
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    Dear Mike,

    thanks for your expert comments and your prediction is absolutely right.

  9. #9
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    Normal values :

    GFR > 90 Normal
    60 - 90. Can indicate chronic kidney disease grade 2.
    30 - 60. CKD 3.
    < 30. CKD 4.
    <10. End stage renal failure, needs replacement (either dialysis or transplant).

    In practice most people with renal disease will be dialysed above 10 and if disease progression is steady, transplanted before requiring dialysis.
    Last edited by KatieBen; 24th February 2010 at 08:07 PM.

  10. #10
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    Today My wife got the report for creatinine clearance test.
    Here is the test result.
    CREATININE ,SERUM BY JAFE METHOD -0.76 mg/dl
    CREATINE URINE BY JAFE METHOD -80.12 mg%
    SPECIFIC GRAVITY OF URINE-1.02
    URINE VOLUME IN 24 HOUR - 2450 ml
    CREATININE 24 HOUR URINE - 1962.94 mg/day
    BODY SURFACE AREA -1.63 square metre
    CRATININE CLEARANCE - 190.37 ml/minute/1.73 sq metre
    Weight : 62 kg
    Height : 162 cm.
    Race -Asian/Indian

    Can anyone suggest whether the test is out of normal range and what will be GFR from the above test.

    Thanks in advance.

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